How long is my cycle?
Count your average cycle length from your last periods and see how much it varies. A first step before talking to your doctor.
Tap the first day of each period you remember
Not sure? Pick your best guess. You can change it any time.
November 2026
Common questions
What cycle length is typical?
A cycle runs from the first day of one period to the day before the next. Lengths differ from woman to woman, and your own pattern matters more than any average. femio gives a fertile window for cycles of 21 to 35 days and says “no confident window” outside that range.
How do I count my cycle length?
Count from the first day of one period to the first day of the next. In the calculator, tap the first day of several recent periods, and it works out your average and how much your cycles vary.
When should irregular cycles be checked by a doctor?
If your shortest and longest cycles are far apart, femio calls your cycles irregular. If you go about three months without a period, or you are trying to conceive and your cycles are irregular, it is reasonable to talk to a clinician now rather than wait.
These calculators give general estimates for learning and planning, not medical advice. Talk to your clinician about your health.